U.S. patent application number 13/975493 was filed with the patent office on 2014-03-06 for tangential indexable cutting insert.
The applicant listed for this patent is Kennametal Inc.. Invention is credited to Rudi Hartlohner, Franz Havrda, Igor Kaufmann.
Application Number | 20140064864 13/975493 |
Document ID | / |
Family ID | 50098044 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140064864 |
Kind Code |
A1 |
Kaufmann; Igor ; et
al. |
March 6, 2014 |
TANGENTIAL INDEXABLE CUTTING INSERT
Abstract
A tangential indexable cutting insert having eight lips which
are distributed in pairs over four side faces of the indexable
cutting insert, each lip being formed by a main lip which is formed
by the intersection of one of the side faces with a base face, a
secondary lip, which is formed by the intersection of the side face
with an adjacent side face, and a corner edge (5) adjoining the
main lip and the secondary lip, is distinguished by the fact that
the main lip has a front portion (4a) which is located at the level
of the corner edge, a rear portion which is located at a lower
level closer to a center axis of the indexable cutting insert, and
a transition portion between the front portion and the rear
portion, the three portions being located in one plane.
Inventors: |
Kaufmann; Igor; (Nurnberg,
DE) ; Hartlohner; Rudi; (Tuchenbach, DE) ;
Havrda; Franz; (Grossenseebach, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kennametal Inc. |
Latrobe |
PA |
US |
|
|
Family ID: |
50098044 |
Appl. No.: |
13/975493 |
Filed: |
August 26, 2013 |
Current U.S.
Class: |
407/114 ;
407/113 |
Current CPC
Class: |
B23B 2200/3681 20130101;
B23B 27/141 20130101; B23B 2200/0471 20130101; B23B 2200/204
20130101; B23B 27/1611 20130101; Y10T 407/235 20150115; B23B
2200/081 20130101; Y10T 407/23 20150115; B23B 2200/369 20130101;
B23C 2200/367 20130101; B23B 27/1607 20130101 |
Class at
Publication: |
407/114 ;
407/113 |
International
Class: |
B23B 27/16 20060101
B23B027/16 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2012 |
DE |
102012017024.6 |
Claims
1. A tangential indexable cutting insert having eight lips which
are distributed in pairs over four side faces of the indexable
cutting insert, each lip being formed by a main lip, which is
formed by the intersection of one of the side faces (3) with a base
face, a secondary lip, which is formed by the intersection of the
side face with an adjacent side face, and a corner edge adjoining
the main lip and the secondary lip, wherein the main lip has a
front portion which is located at the level of the corner edge, a
rear portion which is located at a lower level closer to a center
axis of the indexable cutting insert, and a transition portion
between the front portion and the rear portion the front portion,
the rear portion and the transition portion transition portion
being located in one plane.
2. The indexable cutting insert as claimed in claim 1, wherein the
transition portion extends in a straight line.
3. The indexable cutting insert as claimed in claim 1, wherein the
front portion extends in a straight line.
4. The indexable cutting insert as claimed in claim 1, wherein the
rear portion extends in a straight line.
5. The indexable cutting insert as claimed in claim 1, wherein a
rake face follows profile of the main lip.
6. The indexable cutting insert as claimed in claim 1, wherein a
comparatively small radius (R1) is provided at a transition from
the front portion of the main lip to the transition portion.
7. The indexable cutting insert as claimed in claim 6, wherein the
radius (R1) is around 1 mm.
8. The indexable cutting insert as claimed in claim 6, wherein a
radius (R2) which is larger than the radius (R1) at the transition
from the transition portion to the front portion of the main lip,
is located at a transition from the transition portion to the rear
portion of the main lip.
9. The indexable cutting insert as claimed in claim 1, wherein a
ratio of the length between the front portion, the transition
portion and the rear portion of the main lip are around 1:1:2.
10. The indexable cutting insert as claimed in claim 1, wherein the
front portion of the main lip and the corner edge are located in
one plane.
11. The indexable cutting insert as claimed in claim 1, wherein an
angle (.beta.) between the front portion of the main lip and the
secondary lip is of the order of 70.degree. to 90.degree..
12. The indexable cutting insert as claimed in claim 1, wherein the
corner edge is rounded or arcuate.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a tangential indexable cutting
insert having eight lips which are distributed in pairs over four
side faces of the indexable cutting insert, each lip being formed
by a main lip, which is formed by the intersection of one of the
side faces with a base face, a secondary lip, which is formed by
the intersection of the side face with an adjacent side face, and a
corner edge adjoining the main lip and the secondary lip.
BACKGROUND OF THE INVENTION
[0002] Such an indexable cutting insert is known from DE 10 2007
022 536 A1. The cutting body of this indexable cutting insert is
formed by two in the broadest sense truncated-pyramid-like cutting
body halves which are rotated with respect to one another and merge
into one another by way of their small base faces. The external,
large base faces form the two base faces of the indexable cutting
insert. The side faces extending between the base faces are
configured in an identical manner to one another, such that a total
of eight identical lips are available, said lips being available
successively for machining a workpiece by rotating and/or turning
the cutting insert in the tool holder.
SUMMARY OF THE INVENTION
[0003] The object of the invention is to further develop the known
cutting insert such that an improved cutting performance is
achieved.
[0004] In order to achieve this object, it is provided according to
the invention, in the case of a cutting insert of the type
mentioned at the beginning, that the main lip has a front portion
which is located at the level of the corner edge, a rear portion
which is located at a lower level closer to the center axis of the
indexable cutting insert, and a transition portion between the
front portion and the rear portion, the three portions being
located in one plane. The invention is based on the basic concept
of subdividing the main lip into three portions, the transition
portion being arranged in an oblique manner and, on account of its
orientation, causing a reduction in the passive force during the
machining of a workpiece, that is to say to a reduction in the
restoring force. The reason for this is that the cutting operation
in the region of the transition portion produces a force component
which is oblique to the line which is defined by the front portion
and the rear portion of the main lip. The obliquely oriented force
vector can be broken down into a component which is perpendicular
to this line and a component that acts parallel to this line. The
component acting parallel to the line "pulls" the workpiece toward
the cutting insert, thereby reducing the passive force. As a
result, the forces acting on the workpiece during machining are
reduced and machining precision is increased.
[0005] It is preferably provided that the transition portion, the
front portion and/or the rear portion extend in a straight line. In
this way, the cutting geometry between the main lip and the
workpiece can be controlled easily.
[0006] According to one configuration of the invention, it is
provided that the rake face follows the profile of the main lip.
The resulting step-shaped geometry of the rake face has a positive
effect on chip formation.
[0007] It is preferably provided that a comparatively small radius,
in particular less than 2 mm, particularly preferably of the order
of 1 mm, is provided at the transition from the front portion of
the main lip to the transition portion. Such a radius has been
found to be a good compromise between, on the one hand, an as far
as possible defined start of the transition portion, which is
obtained by a small radius, and, on the other hand, the avoidance
of sharp transitions which could result in local stress
concentrations and damage to the main lip.
[0008] Preferably, a radius which is larger than the radius at the
transition from the transition portion to the front portion of the
main lip is used at the transition from the transition portion to
the rear portion of the main lip. This ensures that damaging load
concentrations at the concave transition between the rear portion
of the main lip and the transition portion are avoided.
[0009] It is preferably provided that the length ratios between the
front portion, the transition portion and the rear portion of the
main lip are around 1:1:2. The comparatively long rear portion of
the main lip ensures that it is possible to work with high cutting
depth during roughing. The relatively short front portion of the
main lip ensures that the advantageous reduction in the restoring
force is already achieved at a comparatively low cutting depth.
[0010] According to one configuration of the invention, it is
provided that the angle between the front portion of the main lip
and the secondary lip is of the order of 70.degree. to 90.degree.,
in particular of the order of 80.degree.. As a result the possible
uses of the indexable cutting plate are increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention is described in the following text with
reference to a preferred embodiment which is illustrated in the
appended drawings, in which:
[0012] FIG. 1 shows a perspective view of an indexable cutting
insert according to the invention;
[0013] FIG. 2 shows a side view of the indexable cutting insert
from FIG. 1;
[0014] FIG. 3 shows a plan view of the indexable cutting insert
from FIG. 1;
[0015] FIG. 4 shows the detail IV from FIG. 3 on an enlarged
scale;
[0016] FIG. 5 shows a perspective view of the indexable cutting
insert from FIG. 1 mounted in a tool holder;
[0017] FIG. 6 shows a side view of the tool holder from FIG. 5;
[0018] FIG. 7 shows a plan view of the tool holder from FIG. 5;
and
[0019] FIG. 8 shows a front view of the tool holder from FIG.
5.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIGS. 1 to 4 show a tangential indexable cutting insert 1
which, couched in simple terms, is defined between two mutually
parallel, square base faces 2 and four similar side faces 3. The
side faces extend between in each case two edges of the base faces
2. With reference to a system of coordinates illustrated in FIG. 1,
a central insert axis A1, which is perpendicular to the two base
faces 2, extends in the Y direction. An axis A2 which is
perpendicular thereto extends in the Z direction and is
perpendicular to two mutually opposing side faces 3. An axis A3
which is perpendicular both to the central axis A1 and to said axis
A2 and extends perpendicularly to the two other opposing side faces
3 extends in the X direction. Located in the plane defined by the
axes A2 and A3 which are perpendicular to the side faces 3 is the
central plane of the cutting insert 1, wherein the two base faces 2
are spaced apart equidistantly from said central plane along the
central axis A1.
[0021] The two base faces 2 of the cutting insert 1 are rotated
with respect to one another about the central axis A1, as can be
seen in FIG. 2. The rotation angle .alpha. of the two base faces 2
is greater than 0.degree. and smaller than 20.degree. and is
preferably 10.degree..+-.5.degree.. Preferably, the rotation angle
is in the region of a conventional and typical clearance angle of
around 6.degree. and is preferably around 8.degree.. On account of
the base faces 2 rotated with respect to one another about in each
case around 4.degree. with respect to the X direction (and likewise
to the Z direction), two cutting body halves 1a and 1b, so to
speak, of the cutting insert 1 are formed, said cutting body halves
1a and 1b adjoining one another or merging into one another in the
central plane (XZ plane) defined by the two axes A2 and A3.
[0022] Each of the similar or identical side faces 3 forms with
each base face 2 a main lip 4 which extends only along a part of
the length of the respective side face 3. In addition, each side
face 3 has mutually opposing rounded or arcuate corner edges 5. The
respective corner edge (corner radius) 5 forms a secondary lip 6
adjoining the respective main lip 4 and extending into the side
face 3 adjoining said side face 3. As is illustrated in FIG. 4, the
angle .beta., as seen in plan view, between the main lip 4 and the
secondary lip 6 is around 80.degree..
[0023] Each cutting edge formed by the main lip 4, corner edge 5
and secondary lip 6 is assigned a chip pocket 7 drawn into the
respective side face 3, that is to say inwardly arched (concavely)
toward the central axis A1. Two chip pockets 7 (just like the
associated main lips 4, the corner edges 5 and the secondary lips
6) are thus located diagonally opposite one another within the
respective side face 3.
[0024] Each main lip 4 is formed by three portions, specifically a
front portion 4a, a transition portion 4b and a rear portion 4c.
The front portion 4a directly adjoins the corner edge 5 and extends
from the latter toward a central plane which is defined between the
axes A1 and A2, and A1 and A3, respectively. In this case, the
secondary lip 6, the corner edge 5 and the front portion 4a of the
main lip 4 are located in one and the same plane. This plane is
indicated by E in FIG. 2 for the front, upper right-hand cutting
corner.
[0025] The front portion 4a of the main lip 4 is adjoined by the
transition portion 4b which extends "inwardly" obliquely to the
plane E. In other words, the main lip 4 extends closer to the axis
A1 in the region of the transition portion 4b. The transition
portion 4b is adjoined by the rear portion 4c of the main lip 4.
Said rear portion 4c extends in turn parallel to the front portion
4a and thus also parallel to the plane E, but at a distance a
"beneath" the plane E, that is to say closer to the axis A1.
[0026] In relation to the plane E, the transition portion 4b of the
main lip 4 drops at an angle of the order of 10 to 15.degree.. As
seen in the side view of FIG. 2, the length ratio between the front
portion 4a, the transition portion 4b and the rear portion 4c of
the main lip 4 is around 1:1:2. All of the portions 4a to 4c of the
main lip 4 extend in a straight line, a transition radius R1 of the
order of 1 to at most 2 mm being located between the front portion
4a and the transition portion 4b. Provided between the transition
portion 4b and the rear portion 4c is a transition radius R2 which
is much larger than the transition radius R1 and is of the order of
5 mm. These examples relate to an indexable cutting insert having
an inscribed circle of three quarters of an inch.
[0027] Each chip pocket 7 has a front portion 7a, a transition
portion 7b and a rear portion 7c, such that the chip pocket as a
whole follows the profile of the main lip. Arranged in the front
portion 7a of the chip pocket 7 is a raised chip breaker 8.
[0028] A central fastening opening 11 through the cutting insert
extends along the axis A1, such that the cutting insert can be
attached to a tool holder by means for example of a fastening screw
or some other fixing means.
[0029] As is indicated in FIGS. 1 and 2, the base face 2 is not
completely flat, but is composed of a planar, internal portion 2a
and external base face portions 2b which recede slightly inward,
that is to say toward a plane defined by the axes A2, A3, in order
to form a flank. However, for the purposes of simplification, the
base face 2 can be assumed here to be generally planar.
[0030] In FIGS. 5 to 8, the tangential indexable cutting insert 1
is shown mounted in a receptacle of a tool holder 20. As can be
seen in particular in FIGS. 6 and 8, the indexable cutting insert
is in this case mounted in a manner rotated about the axes A1 and
A3, such that the in this case active lip having the main lip 4,
corner edge 5 and secondary lip 6 is available at the desired
clearance angles. On account of the transition portion 4b of the
main lip 4 together with the transition portion 7b of the chip
pocket 7, the desired reduction in passive force, in particular
during roughing with a high cutting depth, is produced.
* * * * *